NSH link management now works!  The last fix was to the Ethernet drivers:  They cannot disable clocking to the Ethernet blok on ifdown.  Otherwise, we cannot communicate with the PHY

Change the way PHY interrupts work: disable automatically.  Then we have to re-subscribe each time after the interrupt fires

More of the PHY event notification logic change:  Fix some compile errors when full feature is enabled; Add some missing ioctol logic

Modified to support the change to the network ioctl signature changes.  Also add support for new ioctl to setup PHY event notifications.

Finishes the ioctl definition to subscribe to PHY events. Revamp network ioctl signature to support arguments other than struct mii_ioctl_data.

Add support for an ioctl that can be used to notify an application when there is a change in the network status signalled by a PHY interrupt

libc/time/lib_localtime.c is much closer to NuttX coding style. libc/time/private.h removed; incorporated into lib_localtime.c

When reading the system timer, don't read a struct timespec, convert it to a fake tick count, then back to a timespec.  Remove CLOCK_ACTIVETIME.. it is non-standard, unused, and gets in the way of changes like this